UG supports all the gauges listed on the UG site. However, ultimately the available gauges is vehicle dependent. If the vehicle supports the standardized ECM voltage parameter, then UG will display it. In general the new the vehicle the more likely it is to support ECM voltage
*** UPDATE: With the introduction of the UltraGauge EM version 1.2 on 6/27/12, voltage is now a standard gauge that is always present even when the vehicle does not support it.